Fix bad expect()ations in tests

[dmethvin-gov]

Fixes #227

Several tests were failing but due to incorrect expect() statements it wasn't being detected. I've added an eslint plugin to check that they're done right so the npm run lint task should catch any future ones. I was able to fix most of the tests to pass, I think I got the fixes right but it wouldn't hurt to have some more eyes on this.

@jbalboni I couldn't figure out why this new test was failing, it's part of #267 which recently landed. I'm thinking it's due to the test rather than the code but can you take a look and let me know?

Types of changes

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• I've reviewed the guidelines for contributing to this repository.
• I've checked style and lint with npm run lint.
• I built the production version with npm run build.
• I added tests to verify a bug fix or new functionality.
• All tests pass locally with npm test.
• My change requires a change to the documentation, and I've updated the documentation accordingly.

[annekainicUSDS]

LGTM! Thanks for adding this!